CPT inhibits protein expression and activities of Rac1 and Cdc42, but not RhoA, in a concentration- and time-dependent manner. A, B, LECs, treated with CPT (0–10 µM) for 24 h (A) or CPT (10 µM) for 0–24 h (B), were harvested and subjected to Western blotting with indicated antibodies. b-tubulin was used as a loading control. C, D, CPT inhibited activity of Rac1 and Cdc42, but not RhoA, in LECs in a concentration- and time-dependent manner. LECs treated with CPT (0–10 µM) for 24 h (C) or CPT (10 µM) for 0–24 h (D), were harvested for the small GTPase activity assay as described in “Materials and Methods”.